The present invention relates to a latching relay which provides a particularly positive latching action.
One class of latching relays utilizes a permanent magnet to provide a bistable latch which is switched by a reversal of current in an electromagnetic coil. Foltz U.S. Pat. No. 4,150,348, Goodbar U.S. Pat. No. 3,914,723, Griffith U.S. Pat. No. 4,332,450, and Yatsushiro U.S. Pat. No. 4,383,234 provide four examples of such bistable latches. In each case, magnetic attraction between a permanent magnet and an adjacent movable ferromagnetic element holds a switch in one of two positions. Appropriate polarity of current to a coil is used to cause the latch to switch states. It is important to recognize that in these latching relays the strength of magnetic attraction between the magnet and the adjacent ferromagnetic element determines the force with which the switch is held in its latched position.
The present invention is directed to an improved latching relay which utilizes a mechanical blocking action to hold the relay in its latched position with a force substantially independent of the strength of magnetic attraction between the relevant elements.